Suspicious Betting in a Tennis Match

Nikolay Davydenko looked like a pretty safe bet going into last week’s Prokom Open in Poland. The tennis star was the No. 4 men’s player in the world, the top seed going into the tournament, and, as if that weren’t enough, he won Prokom last year.

Nikolay Davydenko receives treatment on his foot during his second-round match at the Prokom Open. (AP photo)

So when bets were accepted for Mr. Davydenko’s second-round match against 87th-ranked Martin Vassallo Arguello, Mr. Davydenko was the clear favorite — that is, up until about an hour before the match. Then a strange thing happened: In unusually heavy volume on London betting exchange Betfair Ltd., so many people began putting money on Mr. Arguello that he became the favorite to win. And even after Mr. Davydenko clinched the first set of the match, betting on Mr. Arguello continued to increase. Mr. Arguello then won the second set, and in the middle of the third set, Mr. Davydenko abruptly resigned from the match, citing a toe injury and handing Mr. Arguello a victory.

The Arguello bettors were either very lucky, or knew something they shouldn’t have. In any case, their anticipated payday didn’t come through as Betfair, which pairs bettors in around 400,000 contests each year, voided all bets for the first time in its seven-year history. Betfair alerted the Association of Tennis Professionals, which organizes the men’s tennis tour, to what it considered suspicious betting activity, and the ATP is now investigating.

“When a player who is No. 4 in the world drifts off like that, alarm bells start ringing,” Betfair spokesman Robin Marks told me. “It’s against all rational betting patterns.”

Betfair is a large betting exchange where gamblers are matched with bettors willing to take the opposite bet (Betfair takes a small cut, regardless of who wins). Unlike a sports book, where odds are fixed by the bookmaker, the payouts at Betfair fluctuate depending on demand. Until an hour before the match, £1 ($2.03) bet on Mr. Davydenko would pay out just 25 pence (51 cents), according to numbers sent to me by Mr. Marks. By the completion of the first set, Mr. Arguello was paying just 30 pence for a £1 bet, and Mr. Davydenko was paying £3 for the same bet. Overall volume for the match was £3.59 million, or roughly 10 times typical volume for the second-round match of a minor tournament. (Mr. Arguello went on to lose in the third round of the tournament.)

During the Davydenko-Arguello match, Mr. Marks said, members of a 40-person team at Betfair assigned to be “constantly looking at betting patterns, numbers and figures” spotted the suspicious betting activity. The company is now participating with the ATP’s inquiry. “It is important that we not jump to conclusions especially when players’ reputations could be unfairly tainted,” ATP Executive Chairman Etienne de Villiers said in a prepared statement. An ATP spokesman declined to comment further. Mr. Davydenko’s agent told ABC News that Mr. Davydenko “has nothing whatsoever to do” with the betting patterns. Mr. Davydenko is playing in the Rogers Cup this week in Montreal, where he won his second-round match on Wednesday.

The case demonstrates how closely monitoring betting numbers can help alert sporting officials to potential wrongdoing, a point I explored in a recent column about the gambling controversy in U.S. professional basketball. But it also demonstrates that such a system would need to incorporate sports numbers and human judgment.

Benjamin Alamar, editor of the Journal of Quantitative Analysis in Sports, told me that such an early-warning system could look for contradictions between the trend in the match — Mr. Davydenko winning — and the direction of betting. “However, this system would simply indicate that something might be going on,” Mr. Alamar said. To verify, tape of the match would have to be reviewed to see if Mr. Davydenko’s injury was apparent. Mr. Marks told me that a Betfair employee watching the match saw no evidence of injury until a trainer visited Mr. Davydenko in the second round. Another factor is tennis’s varying surfaces: Bettors may have based their wagers on Mr. Davydenko’s three consecutive losses on clay before the Prokom Open, to players ranked Nos. 57, 81 and 50, as pointed out by the sports-gambling information Web site Covers.com.

What do you think was behind the betting patterns in this match? Should Betfair have voided the bets? What sort of early-warning system could be used to detect possible manipulation? Please let me know in the comments.

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